This invention relates to an improved stair tower module and more particularly a stair tower module and system developed for the wind power industry to make wind towers more accessible and improve the efficiency of ingress and egress for authorized personnel.
Existing ingress and egress options available for large wind power tube towers include the open ladder system with fall arrest and the electric lift system. Both of these systems have significant drawbacks because of their significant requirements including, but not limited to, extensive personnel training and certification, special safety equipment such as fall arrest devices, special physical capabilities for personnel, scheduled maintenance requirements and access to electricity. The existing systems limit travel to one person at a time traveling in only one direction at a time making ingress and egress time consuming and inefficient. Those system limitations make emergency response difficult and does not provide for practical emergency exit in case of fire in the top of the wind tower structure.
It is impractical to assemble a conventional stair system inside a horizontal tube; it is also inefficient and expensive to erect stairs inside a vertical tube. The present invention and system allows the stairs to be pre-fabricated into shippable modules at the fabrication plant. The modules are then shipped to the tube manufacture or the jobsite location where they are installed into the tube tower sections while the tube sections are in their horizontal position. Once installed, the tube section can be placed in its vertical position, at the jobsite, giving the workers immediate efficient stair access to accomplish their work in a fraction of the time currently required of the existing system options.
The stair tower module system addresses all the problems associated with the currently available ingress and egress options. No special training or certification is required to access the stair system. As long as authorized personnel stay on the walking surface they are within the guardrails and no special fall arrest devises are required. Further, no special physical capabilities are required of personnel opening up the demographic of people able to access the nacelle (the enclosed top of the wind tower where the majority of the work is performed). Stairs furnished as either hot dipped galvanized steel or a mill finished aluminum, require very little scheduled maintenance throughout the life of the wind tower structure. Unlike an electric lift, the present system does not require electricity making the system available to construction workers as soon as the tube sections are stood up vertically facilitating the installation of the next tower section, nacelle, tower blades and accompanying equipment.
Probably the greatest advantage to the existing stair tower module system is that numerous authorized personnel can utilize the system at the same time, moving in both directions at the same time. Accessible and efficient ingress and egress is absolutely crucial to economically and safely support erection, set-up, maintenance and most importantly emergency response. Stair towers provide the only reasonable way to evacuate workers from the top of tall structures such as wind towers in the case of fire or other emergency exit situations. Cost benefit analysis suggests that the present system could pay for itself much faster than other existing wind tower access systems by reducing the cost of tower installation and future farm operations.